This invention relates to a method and means for configuring and controlling a plurality of functional devices in a multi-function system such as digital memory, multiplexer, arithmetic logic, multiplier, video camera, disk recorder and x-ray devices in a digital fluorography video disk processor system.
An important use of digital fluorography is in making x-ray arteriographic studies. One procedure invloves making a digital representation of an x-ray image, called a mask image, of the blood vessels in an anatomical region of interest at a time when no x-ray opaque medium is entrained in the blood that is flowing through the vessels. The opaque medium is typically an iodine compound solution. Then, when the blood in which the opaque medium has been injected intravenously reaches the region of interest, one or more successive x-ray images are obtained and digitized. One of the images in the series that exhibits the greatest concentration of x-ray opaque medium has the mask image subtracted from it. The mask image usually contains data representative of the blood vessels, other soft tissue and bone. Any subsequent image will contain data corresponding to blood vessels, other soft tissue, bone and iodine. The digital data for the two images are scaled in such fashion that when the subsequent image is subtracted from the mask image, bone and soft tissue substantially cancel each other and the blood containing the x-ray opaque medium remains to define the outline of the blood vessels without the presence of obscuring background information. Customarily, the mask image is stored in one digital full-frame memory and the subsequent images are delivered to another memory. Processing of the data, that is, doing such things as scaling and multiplying, dividing or offsetting it and multiplexing it to one or more video display devices is carried on in the digital video processor (DVP).
Besides carrying out the simple mask subtraction procedure just outlined, the digital video processor is required to perform many other functions for different medical procedures. For instance, some procedures involve multiple subtractions of images and others, by way of further example, require integrating a succession of images and then performing a subtraction. The data flow paths through the digital video processor are necessarily different for the various procedures. The data flow paths are through such functional devices as multiplexers, multipliers, one or more arithmetic logic units (ALU) and look-up tables, for instance. The data flow paths often have to be reconfigured for every image frame, that is, in coordination with the x-ray image acquisition rate. A common approach to reconfiguring the DVP data paths is to use a microprocessor in a conventional manner. The instructions for reconfiguring have been traditionally stored in a read-only memory (ROM). When the microprocessor was instructed to carry out a particular procedure, it fetched the instructions from ROM and executed them in sequence to thereby produce addresses and data for setting up the various functional devices and, hence, data paths in the DVP. If, after the equipment was installed, the user desired to perform some fluorographic procedure which was not programmed in ROM, it became necessary to remove the ROMS from circuitboards, reprogram them and replace them. This is costly if not completely impractical. Thus, programming of procedures in ROM reduces the flexibility of the DVP.